Formula to solve for variable X

Hello all. Nice to meet you.

I have a bit of a kerfuffle as I believe the payroll department for an ophthalmologist I work for is miscalculating my pay. Therefore, I need a formula that will help me solve how many hours I worked for a given pay period; however, the only information I have is my gross pay and my hourly rate. Hence, my pay stubs fail to display my hours worked. Thus, I need to solve for X where X = hours worked. For example, in the following situation I have:

$850.00 Gross Pay
$16.00 Hourly Rate

So, when we divide Gross Pay by Hourly Rate we come up with 53.125 hours worked. Yet, I worked 55 hours his pay period, and I know that because I got paid yesterday, so I know this is wrong. Unfortunately though, for the past 6 years of pay, I cannot recall how many hours I worked each pay period and I have no records of my time cards. I am sure my employer does, but I am not going to start snooping around just yet. I want to apply this formula to all my pay stubs first.

Moreover, I only have stubs that reflect Gross Pay and Hourly Rate, so again, I need to solve for X where X = hours worked.